Look up Alder in Wiktionary, the free dictionary

Alder is the common name of a genus of flowering plants belonging to the birch family. The name may also refer to—

• the Alder Flycatcher, a small bird which nests in the alder.
• a populated place in Montana.

Alder is also the surname of Kurt Alder, the co-winner of the 1950 Nobel Prize in Chemistry for his work on what is now known as the Diels-Alder reaction. The lunar crater Alder was named in his honor.